What are Variable Naming Conventions in JavaScript

While naming your variables in JavaScript, keep some rules in mind. The following are the variable naming conventions in JavaScript:

• You should not use any of the JavaScript reserved keywords as a variable name. These keywords are mentioned in the next section. For example, break or boolean variable names are not valid.
• JavaScript variable names should not start with a numeral (0-9). They must begin with a letter or an underscore character. For example, 123test is an invalid variable name but _123test is a valid one.
• JavaScript variable names are case-sensitive. For example, Name and name are two different variables.

Basic Naming Rules

Here are examples of valid and invalid variable names:

// Valid variable names
var name;
var _2name;
var userName;
var $element;
var firstName123;

// Invalid variable names - these will cause syntax errors
// var 2name;     // Cannot start with number
// var break;     // Reserved keyword
// var first-name; // Hyphens not allowed

Case Sensitivity Example

var name = "John";
var Name = "Jane";
var NAME = "Bob";

console.log(name);  // Different variables
console.log(Name);  
console.log(NAME);  

John
Jane
Bob

Common Naming Conventions

JavaScript developers follow these best practices:

• camelCase: Start with lowercase, capitalize subsequent words (e.g., firstName, userEmail)
• Constants: Use UPPER_SNAKE_CASE for constants (e.g., MAX_SIZE, API_URL)
• Private variables: Start with underscore (e.g., _privateVar)

// Recommended naming conventions
var firstName = "Alice";           // camelCase for variables
var userAccountBalance = 1500;     // camelCase for variables
const MAX_USERS = 100;             // UPPER_SNAKE_CASE for constants
var _internalCounter = 0;          // underscore for private/internal use

console.log(firstName);
console.log(MAX_USERS);

Alice
100

Reserved Keywords to Avoid

These keywords cannot be used as variable names:

// Reserved keywords - avoid these
break, case, catch, class, const, continue, debugger, default, 
delete, do, else, export, extends, finally, for, function, 
if, import, in, instanceof, let, new, return, super, switch, 
this, throw, try, typeof, var, void, while, with, yield

Conclusion

Follow JavaScript naming rules: start with letter/underscore, avoid numbers at start, and don't use reserved keywords. Use camelCase for readability and consistency in your code.